A raising wheel chair is disclosed comprising a wheel frame and a raising frame, said raising frame being connected to the frontal portion of the wheel frame and comprising a seat support with a seat, a backrest support with a backrest and means for maintaining the backrest vertical in the sitting position as well as in the standing position of the user.
Different raising wheel chairs are known to be capable of moving a person from the sitting position to a standing position. The raising wheel chair according to U.S. Pat. No. 5,366,036 also permits the movement of a person into a lying position. Most of the prior art raising wheel chairs have the disadvantage that on a stand-up motion or a sit-down motion a relative motion takes place between the person and the surfaces of the chair making contact with the body of the person. This gives the person an unpleasant feeling and often a so-called shirt pulling effect takes place. To avoid a motion between the backrest and the body of the person in changing from the standing position to the sitting position, and vice versa, U.S. Pat. No. 4,067,249 proposed to pivotally mount the backrest on the rear part of the seat at a distance above the sitting surface, so that the pivoting axis is located in the proximity of the hip joint of the person. This, however, has the disadvantage that in lying position the transfer of the person from the raising chair into the bed is hindered by a protruding part of the chair.
In WO 82/01314 a raising chair is described comprising a seat frame and a backrest frame. In the seat frame a seat is located. The seat frame has on both sides a sidewall to which at the front part and in the region above the hip joint of the user levers are pivotally connected for moving the seat from the sitting position to the standing position. The backrest which is movable in the backrest frame is on both sides pivotally connected with a lever to the seat frame, so that on standing up or sitting down the seat back is moved and no substantial movement between the body of the user and the backrest takes place. However, this raising chair has the disadvantage that the seat frame has on both sides high side walls which prevent a lateral transfer of the user. It is not possible to omit the side walls, because three levers are connected thereto. It is further of disadvantage that the backrest cannot be tilted downward to permit a horizontal position of the user.
French patent application FR 2,589,341 discloses a wheel chair where the backrest has on each side a rod which can be moved in a tube. This permits an adjustment of the highs of the backrest with respect to the user of the wheel chair. The tubes are connected by a horizontal bar which can lifted or lowered by a lifting device, but only the backrest will be lifted whereas Me seat remains stationary.
U.S. Pat. No. 5,366,036 describes a raising wheel chair having arm rests capable of being tilted 90 degrees. Accordingly, if the user is in a lying position, a transfer from the wheel chair to the bed and vice versa is not hindered or made impossible by some parts. In the U.S. Pat. No. 5,984,338 a raising wheel chair is described which permits at least in the sitting position a lateral transfer of the user. However, this raising wheel chair does not permit a lying position and has further the disadvantage that a shirt pulling effect can take place.
The disclosures of all of the foregoing patent documents are hereby incorporated by reference in their entireties.
With reference to FIGS. 1 and 2 a prior art raising wheel chair will be described. The prior art raising wheel chair comprises a wheel frame 11 with a pair of front wheels 13 and a pair of rear wheels 15, and a raising frame 21 comprising a seat 17 and a backrest 20. The raising wheel chair further comprises a footrest assembly 23 with a footrest 24. The wheel frame 11 comprises a tubular construction with two side frames 25 which are connected by struts 27,28.
The raising frame 21 is also a tubular construction. The backrest carrier 19 and the seat support bar 42 are pivotally connected at 29. The backrest support 19 has a lever arm 31 which at 33 is pivotally connected with the parallelogram lever 35. The parallelogram lever 35 is in turn pivotally connected at 32 at the wheel frame 11. The seat support bar 32 is pivotally connected at 22 at the wheel frame 11. By the lever parallelogram 34 formed in this way it is assured that in each position of the chair the backrest 20 will remain in practically the same nearly vertical position. A motor 37 serves for the raising motion from the position in FIG. 1 to the position of FIG. 2 or for the motion in opposite direction for sitting down.